15. THE STARS AND NEBULAE

INDEX



PREFACE


An attempt has been made in these pages to trace the evolution of
intellectual thought in the progress of astronomical discovery, and,
by recognising the different points of view of the different ages, to
give due credit even to the ancients. No one can expect, in a history
of astronomy of limited size, to find a treatise on "practical" or on
"theoretical astronomy," nor a complete "descriptive astronomy," and
still less a book on "speculative astronomy." Something of each of
these is essential, however, for tracing the progress of thought and
knowledge which it is the object of this History to describe.

The progress of human knowledge is measured by the increased habit of
looking at facts from new points of view, as much as by the
accumulation of facts. The mental capacity of one age does not seem to
differ from that of other ages; but it is the imagination of new
points of view that gives a wider scope to that capacity. And this is
cumulative, and therefore progressive. Aristotle viewed the solar
system as a geometrical problem; Kepler and Newton converted the point
of view into a dynamical one. Aristotle's mental capacity to
understand the meaning of facts or to criticise a train of reasoning
may have been equal to that of Kepler or Newton, but the point of view
was different.